.TH "seccomp_merge" 3 "30 May 2020" "paul@paul-moore.com" "libseccomp Documentation"
.\" //////////////////////////////////////////////////////////////////////////
.SH NAME
.\" //////////////////////////////////////////////////////////////////////////
seccomp_merge \- Merge two seccomp filters
.\" //////////////////////////////////////////////////////////////////////////
.SH SYNOPSIS
.\" //////////////////////////////////////////////////////////////////////////
.nf
.B #include <seccomp.h>
.sp
.B typedef void * scmp_filter_ctx;
.sp
.BI "int seccomp_merge(scmp_filter_ctx " dst ", scmp_filter_ctx " src ");"
.sp
Link with \fI\-lseccomp\fP.
.fi
.\" //////////////////////////////////////////////////////////////////////////
.SH DESCRIPTION
.\" //////////////////////////////////////////////////////////////////////////
.P
The
.BR seccomp_merge ()
function merges the seccomp filter in
.I src
with the filter in
.I dst
and stores the resulting in the
.I dst
filter.  If successful, the
.I src
seccomp filter is released and all internal memory associated with the filter
is freed; there is no need to call
.BR seccomp_release (3)
on
.I src
and the caller should discard any references to the filter.
.P
In order to merge two seccomp filters, both filters must have the same
attribute values and no overlapping architectures.
.\" //////////////////////////////////////////////////////////////////////////
.SH RETURN VALUE
.\" //////////////////////////////////////////////////////////////////////////
Returns zero on success or one of the following error codes on
failure:
.TP
.B -EDOM
Unable to merge the filters due to architecture issues, e.g. byte endian
mismatches.
.TP
.B -EEXIST
The architecture already exists in the filter.
.TP
.B -EINVAL
One of the filters is invalid.
.TP
.B -ENOMEM
The library was unable to allocate enough memory.
.\" //////////////////////////////////////////////////////////////////////////
.SH EXAMPLES
.\" //////////////////////////////////////////////////////////////////////////
.nf
#include <seccomp.h>

int main(int argc, char *argv[])
{
	int rc = \-1;
	scmp_filter_ctx ctx_32, ctx_64;

	ctx_32 = seccomp_init(SCMP_ACT_KILL);
	if (ctx_32 == NULL)
		goto out_all;
	ctx_64 = seccomp_init(SCMP_ACT_KILL);
	if (ctx_64 == NULL)
		goto out_all;

	if (seccomp_arch_exist(ctx_32, SCMP_ARCH_X86) == \-EEXIST) {
		rc = seccomp_arch_add(ctx_32, SCMP_ARCH_X86);
		if (rc != 0)
			goto out_all;
		rc = seccomp_arch_remove(ctx_32, SCMP_ARCH_NATIVE);
		if (rc != 0)
			goto out_all;
	}
	if (seccomp_arch_exist(ctx_64, SCMP_ARCH_X86_64) == \-EEXIST) {
		rc = seccomp_arch_add(ctx_64, SCMP_ARCH_X86_64);
		if (rc != 0)
			goto out_all;
		rc = seccomp_arch_remove(ctx_64, SCMP_ARCH_NATIVE);
		if (rc != 0)
			goto out_all;
	}

	/* ... */

	rc = seccomp_merge(ctx_64, ctx_32);
	if (rc != 0)
		goto out_all;

	/* NOTE: the 'ctx_32' filter is no longer valid at this point */

	/* ... */

out:
	seccomp_release(ctx_64);
	return \-rc;
out_all:
	seccomp_release(ctx_32);
	goto out;
}
.fi
.\" //////////////////////////////////////////////////////////////////////////
.SH NOTES
.\" //////////////////////////////////////////////////////////////////////////
.P
While the seccomp filter can be generated independent of the kernel, kernel
support is required to load and enforce the seccomp filter generated by
libseccomp.
.P
The libseccomp project site, with more information and the source code
repository, can be found at https://github.com/seccomp/libseccomp.  This tool,
as well as the libseccomp library, is currently under development, please
report any bugs at the project site or directly to the author.
.\" //////////////////////////////////////////////////////////////////////////
.SH AUTHOR
.\" //////////////////////////////////////////////////////////////////////////
Paul Moore <paul@paul-moore.com>
.\" //////////////////////////////////////////////////////////////////////////
.SH SEE ALSO
.\" //////////////////////////////////////////////////////////////////////////
.BR seccomp_init (3),
.BR seccomp_reset (3),
.BR seccomp_arch_add (3),
.BR seccomp_arch_remove (3),
.BR seccomp_attr_get (3),
.BR seccomp_attr_set (3)
